Flexible plastic floor coverings have been produced for a very long time.
This type of covering generally comprises a thermoplastic base structure which is often reinforced with a textile material embedded in the mass of said thermoplastic.
Also, in order to improve the level of comfort and to provide the covering with insulation and flexibility qualities the reverse surface of said covering may be associated with an underlay, for example a foam underlay.
Furthermore, the upper surface is covered with a finishing layer which provides the floor covering with specific properties such as resistance to UV rays, dirt deposit, scratches, wear, abrasion, etc.
The floor coverings may be produced using different techniques such as coating, calendering, pressing, etc.
In order to create the floor covering using the coating technique a backing sheet is produced by impregnating a reinforcement textile structure, which is generally unwoven, the structure very often being fibreglass based although it can also have a synthetic polymer base, such as polyester, polyamide or polypropylene fibres.
The coating is produced from a plastisol composition, more often than not PVC based, although it can also be acrylic, polyurethane or polyolefin based to provide a smooth, flat surface.
Once the backing sheet has been produced the top layer(s) are created that are intended to provide the decorative and wear-and-tear characteristics. The reverse surface is also produced to ensure the finish (for compact layers) or comfort and/or insulation by associating a mechanical or chemical foam-based underlay.
In addition to floor coverings whose upper surface is flat, for many years now floor coverings have also been proposed that present embossed effects, such as those described particularly in GB-A-1 520 964, U.S. Pat. No. 3,399,106 and U.S. Pat. No. 4,244,899, EP-A-0 003 965 and FR 2 557 905. When these embossed floor coverings are produced a chemical foam, onto which a pattern is printed using inks some of which contain expansion inhibitors, as inserted between the resin-impregnated base structure and the surface layers.
Once the wear layer has been applied to the pattern thus produced, all the layers are gelled together which causes different degrees of expansion between the inhibited printed zones and the uninhibited printed zones and produces an embossed decorative surface, the degree of expansion being lower in the inhibited printed zones.
These types of floor coverings, which have proved to be extremely popular, are widely used nowadays. Nevertheless, they present acoustic and thermal insulation characteristics that are sometimes considered insufficient.
To overcome the drawback the only proposal envisaged therefore consisted in applying a mechanical or chemical foam to the reverse surface which, if a low-density foam is used, can affect the solidity of the covering and the plastic feel provided by this type of underlay often discourages potential buyers.
The level of comfort when walking on the covering is often considered insufficient, comfort being the result of several factors such as the feeling of softness (immediately sinking into the covering) which should be maximum, anti-impact (progressive deceleration) and anti-bounce (nil bouncing speed).